Fifty-five percent of people in the United States test positive to one or more allergens. According to the Asthma and Allergy Foundation, allergies are the fifth most common cause of chronic disease in the United States and third in children. Approximately ten million Americans are allergic to cat dander. Approximately seven percent of allergy sufferers have skin allergies, six percent have dietary allergies, and four percent have insect allergies as of 2007.
Allergen immunotherapy, also known as allergy shots, is a form of long-term treatment that decreases symptoms for many people with allergic rhinitis, allergic asthma, conjunctivitis (eye allergy) or stinging insect allergy. Allergy shots decrease sensitivity to allergens and often lead to lasting relief of allergy symptoms even after treatment is stopped. This makes it a cost-effective, beneficial treatment approach for many people.
Allergy shots work like a vaccine. The body responds to injected amounts of a particular allergen, given in gradually increasing doses, by developing immunity or tolerance to the allergen by producing immunoglobulin G (“IgG”) instead of IgE. Allergy shots are not used to treat food allergies. The best option for people with food allergies is to strictly avoid that food.
There are two phases:
Build-up phase. This involves receiving injections with increasing amounts of the allergens about one to two times per week. The length of this phase depends upon how often the injections are received, but generally ranges from three to six months.
Maintenance phase. This begins once the effective dose is reached. The effective maintenance dose depends on the level of allergen sensitivity and the response to the build-up phase. During the maintenance phase, there will be longer periods of time between treatments, ranging from two to four weeks. Symptoms may decrease during the build-up phase, but it may take as long as 12 months on the maintenance dose to notice an improvement. If allergy shots are successful, maintenance treatment is generally continued for three to five years. Allergy shots have shown to decrease symptoms of many allergies. It can prevent the development of new allergies, and in children it can prevent the progression of allergic disease from allergic rhinitis to asthma. The effectiveness of allergy shots appears to be related to the length of the treatment program as well as the dose of the allergen. Some people experience lasting relief from allergy symptoms, while others may relapse after discontinuing allergy shots.
Allergy is regarded as a Th2 weighted imbalance, and cytokines produced by Th2 lymphocytes, including interleukins 4, 5, and 13, have been associated with the promotion of IgE and eosinophilic responses in atopy. Berger, BMJ, 321:424.1 (2000). Ways to redirect allergic Th2 responses in favor of Th1 responses should be beneficial in reducing incidences of allergic reactions.
In summary, better, and less invasive, means for inducing tolerance to allergens is needed. Rapid, effective desensitization to allergens is a significant unmet medical need that would alleviate a tremendous burden of chronic patient suffering.
It is therefore an object of the present invention to provide methods and compositions to induce tolerance to allergens.